Why do things float?

Answer 1

Because they are less dense than the water. We call the amount of mass in a given volume of space the density. For instance, we could measure the mass of some fresh water in a container. We would then divide the mass of the water by the volume of the container to find the density. However, if we filled the same container with salt water, it would have more mass because the ocean water has the mass of pure water plus the mass of the salt. Since there is more mass in the same volume, ocean water has a greater density then fresh water. For something to float, it must have a density that is less than in what it is floating in. It may seem odd that an enormous ship can float when steel is denser than water. However, if you look at the entire ship you see that there are many places filled with things less dense than water, like air. This means that the density of the entire ship is less dense than that of the water it floats in. To understand why things less dense then water float in water go to the question "Why do some things float but not others?" in the Related Questions section below.
An object floats because it is less dense than whatever it is floating in.

Answer 2

Because of their density.

Water got a density of approxamately 1000kg/m³(Depending of the temperature, this is at room temperatuur).

Everything that has a lower density will float ontop of water. Everything with a higher density will sink.

For example oil, it has a lower density than water so it will float ontop of it.

a rock has definitly a higher density than water so it will sink to the bottom.

Answer 3

Objects float when the buoyant force pushing them upwards is greater than the force of gravity pulling them downward. This happens when the object is less dense than the fluid it is in. The buoyant force acts in the opposite direction of gravity, allowing the object to float or be suspended in the fluid.